Intravenous fluid requirement calculations

One common problem encountered by medical students, nursing students and sometimes even to practicing doctors is intravenous (iv) fluid calculation.

There may be various ways to determine how much maintenance fluid to be given intravenously, however the author will discuss here one commonly practiced technique practiceed by certain medical practitioners.

First you should be oriented with the formula depicted below in the diagram –

To explain the above diagram –

-For body weight of first 10 kgs we give 100 ml/ kg / day.

-For the next 10 kgs we give 50 ml / kg / day.

-Finally, for the remaining body weight i.e. for those weighing more than 20 kgs we give in the rate of 20 ml / kg / day.

For easy calculations it’s good to memorize the amount of iv fluids which might be needed for an individual weighing 10 and 20 kgs.

For a 10 kg person iv fluid required is 10×100 =1000

For a 20 kg person iv fluid requirement is –
1000 + (10×50)= 1500.

If you remember the above two values you can easily derive iv fluid requirements for various body weights more than 10 and 20 kgs.

Now let us consider some examples –

For a 8 kg child- 8×100= 800 ml per day.

For a 12 kg child – 1000+ (2×50) = 1100 ml per day.

For a 30 kg individual – 1500+ (10×20)= 1700 ml per day.

Lastly, how to determine how much iv fluid to be given in each hour. For this simply divide ➗ the calculated total fluid requirement per day by 24; since 24 hours makes a day.

The above writing is a simplified version for iv fluid requirement calculation made by the author which may not be free from errors. Hence, please cross check the information from reliable sources. ⚠